Hi Abhijeet,
not in all cases you can get (or get full) crystal structure from database. Then, additional EXAFS experiments can be helpful. Of course, you can also imagine more situation, as doping, vacancies or substitutions, etc. You can also try to create crystal model without XRD data.
Please, do not forget that EXAFS is the element selective method, and probes the structure locally.
Answering the third question - if you have EXAFS data, and model of crystallographic structure you can compare both, and if it is needed adjust/model the structure to get better agreement. If you use know structure from another compound you should be sure that you have replaced elements according to elements, ocupancy and positions in your sample.
regards
kicaj

W dniu 11-01-30 09:23, Abhijeet Gaur pisze:

Hi all,

          As I understand, the EXAFS fitting procedure using Artemis, for generating a theoretical model requires the crystal structure parameter like space group, cell parameters and specially atom coordinates etc. For this we have to perform XRD measurements of single crystals of the samples. I have some questions

(1) In case we dont have the XRD data of a sample then how can the EXAFS

      analysis be done of that sample?

(2) If we have already performed the XRD on the sample then by doing

     EXAFS what additional information are we getting ?

(3) If the answer to the first question is that - use the crystal structure of a

      similar sample, then what are the conditions under which we can use the

      known crystal structure of one sample for other samples ?

Thanks in advance

Abhijeet Gaur
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